Intraspecies Combat Probably Practiced by Roadian Permian Anomodonts Tiarajudens & Anomocephalus

Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana

Authors:

Cisneros et al

Abstract:

Anomodontia was a highly successful tetrapod clade during the Permian and the Triassic. New morphological information regarding two bizarre basal anomodonts is provided and their palaeoecological significance is explored. The osteology of the recently discovered Tiarajudens eccentricus Cisneros et al. 2011, from the Brazilian Permian, is described in detail. The taxon exhibits unusual postcranial features, including the presence of gastralia. Additional preparation and computed tomography scans of the holotype of Anomocephalus africanus Modesto et al. 1999 discovered in the Karoo Basin of South Africa allow a reappraisal of this genus. Anomocephalus is similar to Tiarajudens with regard to several traits, including a battery of large, transversally expanded, palatal teeth. Molariform teeth are present in the mandible of the African taxon, providing additional insight into the function of the earliest tooth-occlusion mechanism known in therapsids. At least two waves of tooth replacement can be recognized in the palate of Anomocephalus. The outsized, blade-like caniniforms of the herbivorous Tiarajudens allow several non-exclusive ecological interpretations, among which we favour intraspecific display or combat. This behaviour was an alternative to the head-butting practised by the contemporary dinocephalians. Combat specializations that are considered typical of Cenozoic herbivores likely evolved during the Middle Permian, at the time the first communities with diverse, abundant tetrapod herbivores were being assembled.

Pre Guadelupean Permian Extinction Lagerstätte Found in Antarctica

A high-latitude Gondwanan lagerstätte: The Permian permineralised peat biota of the Prince Charles Mountains, Antarctica

Authors:

Slater et al

Abstract:

The Toploje Member chert is a Roadian to Wordian autochthonous–parautochthonous silicified peat preserved within the Lambert Graben, East Antarctica. It preserves a remarkable sample of terrestrial life from high-latitude central Gondwana prior to the Capitanian mass extinction event from both mega- and microfossil evidence that includes cryptic components rarely seen in other fossil assemblages. The peat layer is dominated by glossopterid and cordaitalean gymnosperms and contains moderately common herbaceous lycophytes, together with a broad array of dispersed organs of ferns and other gymnosperms. Rare arthropod-plant and fungal-plant interactions are preserved in detail together with a plethora of fungal morphotypes, Peronosporomycetes, arthropod remains and a diverse coprolite assemblage. Comparisons to other Palaeozoic ecosystems show that the macroflora is of low diversity. The fungal and invertebrate-plant associations demonstrate that a multitude of ecological interactions were well developed by the Middle Permian in high-latitude forest mires that contributed to the dominant coal deposits of the Southern Hemisphere. Quantitative analysis of the constituents of the silicified peat and of macerals within adjacent coal seams reveals that whilst silicified peats provide an unparalleled sample of the organisms forming Permian coals, they do not necessarily reflect the volumetric proportions of constituents within the derived coal. The Toploje Member chert Lagerstätte provides a snapshot of a rapidly entombed mire climax ecosystem in the closing stages of the Palaeozoic, but prior to the onset of the protracted crisis that engulfed and overthrew these ecosystems at the close of the Permian.

Academic Bun Fight: Is There a Gap in the Middle Permian Strata?

Apparently back in 2005, Spencer Lucas argued there was a 2 to 3 million year gap in the known strata producing a hiatus.

Fossils of tetrapods (amphibians and reptiles) have long been used to correlate regionally Permian nonmarine strata (Lucas, 1998).
However, the development of a global Permian tetrapod biostratigraphy and biochronology has been hampered by several problems. The most serious may be the presence of a global gap (hiatus) in part of the Middle Permian record of tetrapods.

Michael Benton wrote in 2012 there is no gap in the Middle Permian Strata based on global evidence:

During the Permian, tetrapods showed a major transition from basal synapsid-dominated faunas in the first half to therapsid-dominated faunas in the second. The transition was significant in marking the beginning of richer and more complex communities, a precursor to modern terrestrial ecosystems. This changeover may have been gradual or abrupt, but its study has been complicated by the postulated occurrence of a substantial hiatus in the fossil record, termed “Olson's Gap”, which obscured the nature of the turnover. New evidence from redating of key tetrapod-bearing units of the American southwest and European Russia confirms that there is no gap in the fossil record of Permian tetrapods. Indeed, evidence for substantial sampling bias in the Permian tetrapod fossil record as a whole is queried.

Spencer Lucas replied in 2013:

Benton (2012) claims that there is no gap in the Middle Permian tetrapod fossil record, in contrast to my (2004) conclusion that a gap exists between the youngest pelycosaur-dominated tetrapod assemblages and the oldest therapsid-bearing tetrapod assemblages. I referred to this as Olson’s Gap and concluded that it is equivalent to most of the Roadian Stage. Instead, Benton (2012, his figure 1) correlates the youngest pelycosaur assemblages from Texas-Oklahoma with the oldest therapsid assemblages of Russia. However, in advocating this correlation, Benton does not address an extensive marine biostratigraphic database detailed by me (2004).

To which Benton replied in 2013:

In his comment, Lucas (2013) reiterates his earlier view that there was a marked gap in the tetrapod fossil record spanning the Roadian and Wordian of the Middle Permian, which I, and others (Reisz and Laurin 2001, 2002), have opposed. His arguments are far from certain, however. He says that the uppermost tetrapod-bearing terrestrial Permian beds in Oklahoma and Texas (United States) are Early Permian in age, and that the oldest Russian tetrapod-bearing beds are post-Roadian, so leaving a temporal gap of 2–3 m.y. On the first point, his view is not accepted by the majority of researchers, although the biostratigraphic evidence is far from watertight, and on the second, he is opposed by the majority of experts.

Permian Parasite Fossil

A cluster of tapeworm eggs discovered in 270-million-year-old fossilized shark feces suggests that intestinal parasites in vertebrates are much older than previously known, according to research published January 30 in the open access journal PLOS ONE by Paula Dentzien-Dias and colleagues from the Federal University of Rio Grande, Brazil.

Remains of such parasites in vertebrates from this era are rare- of 500 samples examined, only one revealed the tapeworm eggs. This particular discovery helps establish a timeline for the evolution of present-day parasitic tapeworms that occur in foods like pork, fish and beef. The fossilized eggs were found in a cluster very similar to those laid by modern tapeworms. Some of them are un-hatched and one contains what appears to be a developing larva. According to the study, "This discovery shows that the fossil record of vertebrate intestinal parasites is much older than was previously known and occurred at least 270-300 million years ago."